Hi there, jkrumpfer.
 

The steps posted by Mark_R are for QuickBooks Desktop. I'd be more than happy to guide you through deleting transactions in QuickBooks Online.
 

Here's how:

1. In your left navigation bar, go to Banking, then access the Banking tab.
2. Pick an account to work with by clicking its tile. It will highlighted in blue.
3. Choose each record you'd like to delete by ticking their checkboxes.
4. Hit Exclude.
   
5. Go to your Excluded screen, then select the transactions.
6. Click Delete.
   

I've additionally included a detailed article about excluding downloaded transactions that may come in handy moving forward: Exclude downloaded bank transactions
 

Please feel welcome to send a reply if there's any questions. Have a lovely day!